This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Magnetization transfer ratio has been shown to correlate well with collagen content in biological tissue. Previous studies have shown that the nucleus region of intervertebral disc contains significant concentration of randomly oriented type 11 collagen fibers. However, the nucleus collagen content's response to age-related degeneration has not been thoroughly investigated, while the proteoglycan content has been shown to consistently decrease with degeneration. In this study, we will use magnetization transfer ratio maps of young and old subjects to investigate the change in collagen content occurring in disc nucleus as a result of degeneration. The degree of interverbral disc degeneration will be independently assessed via T2-weighted MR images according to the Pfirrmann scale. Grading as well as clinical assessment of the intervertebral discs will be carried out by a board-certified radiologist. Correlation analysis between magnetization transfer ratio and Pfirrmann grade will elucidate the fate of nucleus collagen content in intervertebral disc degeneration. In order to minimize direct saturation effect, we will apply the saturation pulse at an off-resonance frequency of 6.4 kHz. Imaging will be carried out on a Siemens 1.5T Sonata MRI scanner. A custom programmed centrically-encoded TSE pulse sequence with the option of off-resonance saturation will be used to collect the images required to compute magnetization transfer ratio maps.